Brushcutters of the kind described above are known and are equipped with either a curved protective tube or with a straight protective tube. The protective tube supports a cutterhead at one end and a drive motor at the other end. The drive shaft connecting the motor with the cutterhead is supported within the protective tube by at least one bearing sleeve unit. For this purpose, the bearing sleeve unit includes radial supporting ribs which extend in the longitudinal direction of the protective tube.
No tolerance differences should occur when the bearing sleeve unit is built into the protective tube. If the bearing sleeve unit is undersize, then the supporting ribs are not in radial contact engagement with the protective tube so that the bearing sleeve unit defines a clearance space with the protective tube and can be subjected to radial oscillations therein. On the other hand, if the bearing sleeve unit is oversize, then forces develop which are applied to the supporting ribs and these forces are directed radially inwardly when the bearing sleeve unit is built into the protective tube. These forces can deform the bearing sleeve unit and severely limit its journalling characteristic.
However, disadvantages occur even when a bearing sleeve unit is seated in the protective tube with a precise fit. Oscillations and vibrations produced by the drive shaft are transmitted directly to the protective tube because of the considerable radial stiffness of the bearing sleeve unit. These oscillations and vibrations are disturbing to the operator. An amplified radial force is applied to the bearing sleeve unit because of the ovalization of the protective tube in the region thereof which is bent whereby the bearing sleeve unit becomes deformed.